public class Animal {
    public int age;
    public int weight;
    public String eat() {
        return "饱餐一顿";
    }
    public String sleep() {
        return "睡觉";
    }
    public Animal() {
        System.out.println("You build an animal.");
    }
    public Animal(int age, int weight){
        System.out.println(String.format("You build an %dyears old animal with %dkg weight.", age, weight));
    }

}
